Looking for Madrid train station recommendations

I don't have particular food recommendations for you, but a pre-made sandwich on an earlier train would be my first choice.

The 6-hour buffer is safe—maybe well more than needed. Most Renfe tickets can be changed, sometimes for a fee. So if you get to Atocha 4 hours before your scheduled train, you might want to go to the window and see if you can switch to an earlier departure.

I hope you wouldn't have to go through the regular ticket line to make a change. Those lines are hours long. I am not exaggerating; I was in line for three hours. This is a chronic issue at Atocha Station. It's highly likely that you'd miss the earlier train you wanted to take while standing in that line.

I don't know whether an on-the-spot change could be managed at the airport train station, but I'd try for that. Or maybe there's a Renfe app you could use.

Sorry that I can't help with restaurant recommendations, but there's no shortage of places in the area. I'd head north and--in the absence of advice from those in the know--would look on the streets NE of Calle de Atocha. If you have extra time to spend outdoors, fending off jetlag, the Botanical Garden is very near Atocha Station. It has an entrance charge. Nearby Retiro Park is free.

Thank you for the comments.
We wanted the fastest option to Seville after flying into Madrid airport at 13:40.
Next AVE train to Seville was at 1800.

If per chance there is an earlier train we can take, we'll evaluate lines when we get to the train station.
In the meantime, I was just hoping for some restaurant recommendations around the train station.
I'm sure all of this will be an interesting travel story in the end!

I contrast acraven on this -- the area past Calle de Atocha is getting too close to the Prado and is full of touristy spots; if you want affordable local eats try going northwest instead of northeast from the train station to get into the scene around the university.

Or go over to Retiro park as mentioned earlier.